I thought of that proverb, and of my time as a prosecutor in Haiti, when Jean-Claude "Baby Doc'' Duvalier returned to Haiti this week. Under the presidency of Duvalier and his Tonton Macoutes militia, thousands were killed and tortured, and hundreds of thousands of Haitians fled into exile. A prosecutor has charged Duvalier with embezzlement and former detainees have filed complaints for torture.

Doesn't Haiti have enough to worry about, one might ask, without prosecuting Duvalier?

On the contrary, bringing Duvalier to justice and giving him a fair trial, would show Haitians that the state still functions, that it can still perform the most basic of duties -- punish those who commit the worst crimes. If Baby Doc gets away with everything he did, how can the authorities hope to dissuade street gangs from using a little force?

The question goes to the heart of one of the Haiti's most fundamental problems: throughout its history, repressive rulers and their henchmen have literally gotten away with murder. The law has been used to reinforce the domination of a small elite over the great mass of poor peasants and has almost never functioned to punish even the worst massacres. Even when dictatorial leaders such as Duvalier have been overthrown, they have usually been allowed to leave the country safely to join their bank accounts. As a result, the Haitian poor justifiably have had little faith in the Haitian state in general and the legal system in particular.

In 1995, after a three-year reign of terror -- perhaps Haiti's worst -- I was hired by the government of President Jean-Bertrand Aristide to prosecute those crimes. The military government of Raul Cedras and its paramilitary allies had killed 3,000 to 5,000 people, mostly grass-roots activists and the poor.

The size of our challenge -- to empower the poor by providing official recognition of the importance of their suffering -- was matched by the obstacles arrayed against us, obstacles that largely still exist today. The popular thirst for justice was not reflected in a judiciary and legal profession largely drawn from the small upper strata of Haitian society. There had been a deliberate decision by the United States not to disarm former soldiers and paramilitary agents, and fear of them still stalked the country, inhibiting people from coming forward to denounce perpetrators of abuses.

Even when their class bias did not get in their way, judges had little incentive to order the arrest of armed criminals -- judges regularly snuck out of their offices when they saw us coming. The failure to put known criminals away created a vicious cycle as even brave people saw little benefit in stepping forward.

It took several years of dogged persistence before, in 2000, my successors obtained, in the most significant human rights trial in Haitian history, convictions of 53 officers and soldiers for a massacre in the Raboteau slum of Gonaives city. Five years later, under a new de facto government, a court overturned those convictions in an internationally condemned ruling, and impunity again reigned supreme.

Haiti's earthquake has further diminished the capacity of the state and has almost totally undermined its ability to safeguard fundamental rights. Chronic problems such as violence against women and inhumane prison conditions have been exacerbated. Most of those who escaped from jail during the earthquake (almost none of whom had ever been tried) remain at large. The failures of reconstruction and confused elections have further eroded government legitimacy. In this context, the prosecution of Duvalier could kick-start the system and help to begin building the state institutions that Haitians deserve.

Duvalier may have forgotten the blows he gave to the Haitian people, but the people remember.